Exhaust gas emitted from an internal combustion engine, particularly a direct injection diesel engine, is a heterogeneous mixture that contains gaseous emissions such as, but not limited to, carbon monoxide (“CO”), unburned hydrocarbons (“HC”) and oxides of nitrogen (“NOx”) as well as particulate matter (“PM”) comprising condensed phase materials (liquids and solids).
Typical exhaust gas treatment systems include a particular filter (“PF”), such as a diesel particulate filter, to collect the particulate matter from the exhaust gas. A pressure sensor may also be included in the exhaust gas treatment system to detect the pressure associated with the PF. The pressure detected by the pressure sensor varies according to accumulation of PM in the PF and/or a damaged PF. In addition, the exhaust gas flow rate of the exhaust gas may vary the pressure detected by the pressure sensor. However, normal operating conditions of the vehicle, such as sudden accelerator pedal manipulation, may also vary the exhaust gas flow rate. Therefore, monitoring the instantaneous pressure associated with the PF may not accurately distinguish a faulty PF from normal operating conditions of the vehicle.